Plastic molding machine



" Oct. s, 1946.

A. A. BURRY PLASTIC MOLDING MACHINE Filed Nov. 11 1943 5 Sheets-Sheet l 0 Infeh I01:

Oct. 8, 1946. A. A. BURRY PLASTIC MOLDING MACHINE S SheetS-Sheet 2 Filed Nov. 11, 1943 0ct..8, 1946. A. A. BURRY 2,408,911

PLASTIC MOLDING MACHINE Filed Nov. 11, 1943 5 Sheets-Sheet 3 3, 1943 A. A. BURRY 2,408,911

PLASTIC MOLDING MACHINE Filed Nov. 11, 194: 5 Sheets-Sheet 4 Inr n for.

0a. s, 1946. I A. A. BURRY 2,408,911

PLASTIC MOLDING MACHINE Patented Oct. 8, 1946 PLASTIC MOLDING MACHINE Arthur A. Burry, Toronto, Ontario, Canada, assignor to Cyril Fuller Application November 11, 1943, Serial No. 509,936

Claims.

This invention relates to machines for moldine articles from plastic materials under extremely heavy hydraulic pressure and the principal objects of the invention are to provide a machine in which the faces of the molding die blocks will be held in contact during the molding operation under hydraulic pressure, overbalancing the pressure of the plastic injection mechanism so that the articles produced will be perfectly formed and free from fins caused by leakage of the plastic between the mold faces.

A further important object is to devise a mechanism in which the dies will be separated instantaneously following the completion of the injection operation so that the molded articles may be cleared from the dies with great rapidity and before the material has become chilled.

A still further object is to devise a machine in which the stresses are uniformly distributed between the several moving elements, thereby relieving excess stresses at any particular point in the structure.

One of the principal features of the invention consists in the novel construction and arrangement of a locking toggle between a movable die holder and a fixed abutment whereby the die holder may be operated to close the die carried thereby against the opposing die and to be moved away from same with a rapid reciprocating movement free from endwise pressure, a hydraulically operated member being interposed between the said toggle and the fixed abutment to apply a final closing pressure between the dies.

A further feature of importance consists in the novel construction and arrangement of hydraulic means for breaking the toggle and moving the dies apart and for returning the movable die holder and toggle into closed position.

A still further feature of importance consists in the flexible coupling of the stationary die holder with the cylinder of the injection ram whereby hydraulic pressure is applied to pull the cylinder into operative contact with the stationary die in opposition to the pressure exerted by the injection plunger.

In the accompanying drawings:

Figure 1 is a plan view of my improved molding machine.

Figure 2 is a side elevational view of the machine.

Figure 3 is an enlarged vertical longitudinal mid-sectional view of the abutment end of the machine and the movable die holder and toggle mechanism taken on the line 3-3 of Figure 1.

Figure 4 is a part vertical elevation and half section taken on the line 4-4 of Figure 3 or the toggle operating mechanism.

Figure 5 is a horizontal sectional view of the abutment end of the machine taken on the line 55 of Figure 3.

Figure 6 is an enlarged longitudinal sectional view of the injection plunger cylinder and heater taken on the line 6-6 of Figure 1.

The machine herein shown and described comprises a base I having a horizontal bed plate 2 at one end thereof on which is rigidly mounted an abutment 3 through which extends a pair of horizontal tie rods 4, the inner ends of which are anchored in a flange 5 extending transversely of the base intermediate of its length.

A pair of horizontal tie rods 6 arranged above the rods 4 and parallel therewith are secured at one end in the abutment 3 and the inner ends extend through a die block holder I which is slidably mounted on the tie rods 4 adjacent to the flange 5.

A die block holder 8 is slidably mounted on the Slidably mounted in the cylinder orifice I4 is a l piston block H which has a reduced end extending beyond the shoulder l5 and spiral compression springs l8 housed in recesses in the piston engage the shoulder and urge the piston inwardly toward the end block IS.

The inner end of the piston I! is spaced from the inner end of the block I B and both the piston and block are provided with flanged washers l-9 held in position by centre plates 20 secured by suitable countersunk screws.

A port 2| extends through the base of the abutment 3 midway between the inner ends of the piston I1 and block l6 and is connected to a suitable valve-controlled source of hydraulic pressure supply.

The piston block I! is formed with a part-cylindrical recess .22 in the end projecting from the cylindrical orifice and in this recess is secured by transverse bolts 23 a cylindrical member 24 which is provided with reduced trunnion ends 25.

Rotatably mounted on-the...trunn.ion ends 25 are a pair of side plates 26 which are formed with outwardly extending bearing trunnions 27 arranged intermediate of their length.

A plate 28, preferably of hardened steel, is secured between the side plates 26 with one end snugly abutting the cylindrical member 24 secured to the piston, and the other end thereof is curved to correspond to the curvature of the face I 2 of the block I I, said curvature,being pref erably theuarc of a circle, the centreof which ,is

located above the axial centre of the member 24 on which the side plates swing so that the plate;

28 will swing up and clear the curyed face of the block I I.

Mounted on the'trunnions v2'I are apai n of links 29 which extend, alongside the plate s ;;28.gg-

and are pivotally connectedto trunnion extensions 30 on the sides of the lug'-9-of the diebl'ock the jaw is pivo tally fmounteda plunger rod 33."

A piston. 34 is" mounted on the rod .33 and operateswithina cylinder 35 arranged in substantially right angular relationto the'plate 28,-and pivotally mounted intermediate of its length on hollowedv gudgeons 36-suppo rted in brackets 31 secured tothe underside of the bed plate 2 either side of a s1ot 38.

Oneor the hollow gudgeons 36 is connected with 'a port 33:1eadingto the bottom end of the cylinder 35,"and the other of said gudgeons is connected to a port 40 leading to the top of the cylinder. j Suitable t'ubularconnections are provided with each of the gudgeons to conduct hydraulic' pressure respectively-to the bottom and top-of; thecylinder and to provide alternately for the exhaust of pressurefluid.

Itwill be understood that by the application of fluid-pressure within the cylinder 35 against the bottom end of the piston 34, the piston and plunger-rod 33 are forced upwardly; the pressure fluid exhaustingthrough the port 40 The upward movement; of the rod 33' lifts the plate 28 swinging it on its; trunnion bearing supports on the' ends of themember 24. i

It will be understoodthat there is no binding pressure between the face I2 of the block II and the'plate 28 due to the pressure of the springs I 8 against the piston, forcing it inwardly toward the end block I6, there being--nofiuid pressure between the said block I6 and piston.

As the plate 28 is swung upwardly through the raising-of the piston 34 the side links 28 exert a longitudinal pullupon the trunnions of the block 8, thereby sliding the block, and the die block carried thereby} toward the abutment,

thereby-pulling the die m mma-ma by the block- I 8 away-from the die block c'alrried by the block a I, so that the faces of the dies are separated a sufilcient distance to allow the articles molded with thedies to be moved clear or the dies The slidable block 8 is provided with a transverse slot 4I in which is mountedQafknock-out bar. 42 which is provided with suitable. pins extendinglthrough theblock 8' to push the molded'articles out of the die. The bar 42 is held in the release position by coil compression springs 43. The ends of the bar 42 project beyond the block 8, as illustrated particularly in Figure 5, and are adapted to engage the ends of rod members 44 threaded in lugs 45 extending from the abutment 3.

The threaded rods 44 may be adjusted to any desired position .so that-the free ends, thereof wilt. engage the;jknock-outtflbar 42 as; the block 8 is moved by the upward operation of the toggle, and by the manipulation of a suitable valve mechanism, which may be controlled by the upward-swinging of the plate 28 or the longitudinalinovement of the die block holder 8, fluid pressure'to the cylinder 35 may be reversed, that is to say, the port 39 leading to the bottom of thecylinder will be-connected to exhaust and the port. 40-will be connected to the pressure side of a suitable hydraulic fluid supply.

Fluid thus entersthe top of the cylinder and forcesthe piston 34 downwardly, thereby swinging the' plate 28; and through the toggle, returning the die-holding block 8 to its original position," the plate 28 having its arc-shaped face brought intosnug engaging contact with the curvedface I 2- of the block II.

This movement of the block 8 brings the die faces-into close engagement and through the manipulation of a suitable control switch 45' engaged by the plate 28; or any other part of the toggle mechanism; the valve controlling the inlet of hydraulic-pressure fluid to the port 2I is open,--and the pressure fluid flowing in between the block- IBand piston ll applies endwise pressureto the piston which is transmitted along the horizontalcentre line through the block 24, the plate 28 and the block II to the block 8 carryingthedie, thus applying hydraulic pressure to force the contact faces of the dies together with a pressure that willprevent leakage of the plastic materialwhich will then be forced into the die.

The die-holding block '1, which is mounted on the. lower tie rod 4, engages the flange 5 to resist the'Iendwise pressure exerted thereagainst by the hydraulic fiuid directed against the piston I1. Theiupper side of the block 1 also engages the limiting nutof-the upper tie rods 6.

ThehaseLI is provided with'a bed plate 48 on whichfi's. mounted, for limited endwise displacemerit, a frame 4.! which has longitudinally spaced vertioalflangesnn and 49. A cylinder 50 is secured to the .outward face of the flange 48 and operatingin said. cylinder. is a piston 5|, the plunger..52.-of which .extends through a suitable packing .boxin the flange 48.

A ram-i 53.:is. secured in the.end of the plunger and extends through an orifice in the flang 49 andslidablyengages .a tubular liner 54 mounted 'ina cylindricalflanged spacing member 55 securedi tdthe. flange .49..

A chute ifigextending. from a suitabl hopper containingethe, powdered plastic material, enters.- the gspacer;and; ;liner intermediate/poi its length and feeds the material into thellinenin frontof spacer member 55-by a grooved clamping ring 58;

'a bushing 58 being interposed between the end of the= l iner -4 and the cylinder.

The construction of the heater cylinder does not formp'artof this nvention but the surrounding heater proyides a temperature which serves to plasticize the material forced through the bore thereof by the operation of the ram 53, and thepressure applied to the die block through the piston ll arranged in the abutment 3.

The operation of the plunger piston for injecting the plastic material into the mold will be controlled by suitable switches to follow immediately after the application of pressure to the dies through the piston l1.

With the endwise pressure exerted against the plastic by the plunger it has the tendency to force the cylinder, the spacer member and the heating cylinder 51 away from its contact with the die blocks, and in order to obviate this and the consequent leakage of the plastic around the nozzle end of the injection cylinder, I provide a pair of hydraulic cylinders 6] arranged at either side of the spacer member and connected to the flange 49 of the frame 41.

The plungers 62 of these cylinders 61 are connected to lugs 63 formed at either side of the block I.

'Hydraulic pressure is directed into the ends of the cylinders 61 closest to the block I through conduits 54, and the pressure directed thereinto operates against pistons carried by said plungers within the cylinders 6| to create a direct pull upon the plungers 62 and the block 1, holding the block I and its die in close engaging contact with the end of the heater cylinder nozzle.

Suitable switches and levers are arranged in a panel 65 on the side of the base to effect the necessary control for starting and stopping, and suitable valves and other devices are arranged within the :base I for controlling the time period of movement of the different elements. i

A machine constructed as described is found an opposing pull exerted by'the plungers in the cylinders which are attached to the frame carrying the main cylinder and their plungers are connected to the block I as described. Thus a pull is exerted in one direction on the block 1 to counteract the pressure against the block. exerted through the injection plunger.

This equalization of pressures eliminates the necessity of. fine adjustment in the setting of the main plunger cylinder and its connected parts and also avoids the necessity of providing extremely heavy main frame structures.

The pressure applied to the meeting die blocks through the operation of the piston ll arranged in the abutment 3 is transmitted from the abutment 3 to the flange 5 and substantial equalization occurs through the pull in the opposite direction exerted upon the block 1 by the plungers in the cylinders 6|.

The arrangement of toggle mechanisms herein described is extremely important. As the toggle operates freely through the manipulation of the vertical plunger 33 in the cylinder 35 the bearings and joints are not operatedunder pressure, but after the toggle has been 'closedpressure is applied hydraulically by the introduction of the hydraulic-fluid through the port 2| to iorcethe piston 11 andits connected parts to apply the pressure directly through the locked toggle to the die block.

It will be noted that the cylinder 35 is mounted on horizontal pivots so that the cylinder swings freely in a vertical plane in raising and lowering the toggle.

It will be readily understood that contact making and breaking'devices may be arranged at various parts of this mechanism to operate relays 'for the control of suitable time-controlled valves so that the sequence of operation will follow in the proper order and with the proper timing.

Assuming that the desired dies are properly secured in position on the die holders 1 and 8 and the dies have been brought together face-toface, the plate 28 will be in a horizontal position,

as indicated in Figure 3, and by the operation of a valve hydraulic pressure is'admitted through the port 2! to apply pressure back of the piston H and thereby force the die blocks together.

Immediately following the application of this hydraulic pressure against the dies a suitable controlled valve is opened to admit hydraulic pres- Hydraulic pressure is constantly applied to the cylinders 6| so that the die block carried by the holder 1 will be held tightly against the nozzle 66 to prevent leakage of the plastic material.

At the completion of the stroke of the piston 5| and its plunger 53 suitable valves will be automatically operated to connect the ports 66 at the inner end of the cylinder 50 with the hydraulic pressure supply and to open the port 6| to exhaust, thereby reversing the travel of the piston 5| and the plunger 53.

Following the operation of the valve to efiect the return movement of the plunger 53 the valve controlling the pressure through the port 2| against the piston I! will be closed and the pressure allowed to exhaust.

Immediately following the release of pressure against the piston ll hydraulic pressure is directed through the port 39 to the bottom end of the cylinder 35 to force the piston 34 therein in an upward direction, operating the hinged plunger 33 to swing the plate 28 upwardly, and simultaneously operate the toggle links 29 to pull upon the block 8, sliding it on the longitudinal tie rods and separating the die blocks.

The movement of the block 8 effected by the operation of the toggle brings the knock-out bar 42 into contact with the adjustable rods 44, and the movement of the bar 42 is arrested while the block 8 continues to move, thereby forcing suitable knock-out pins connected to the bar 42' or engaged thereby to push the molded articles out of the die cavities from where they will fall into a suitable receptacle.

Upon the completion of the upward stroke of the plunger 33 and the operation of the toggle and the block 8 the flow of pressure fluid through the port 39 is closed and the port is open to exhaust,

while ,-simu1taneo.usly the suretfluidand the;plu nger'33is -moved :dOWl'l wardly, thereby swinging theeplate' 28 and the togglelinks downwardly so that the block ,8 is:

moved horizontally ;to I bring-the diescarried. thereby back into face contact with the dies ,carrried bythe block 1.

Inthe meantime the flow of pressure fluid to the, vplunger cylinder 50 has been automatically discontinued on the completion of the returnstrokelpf the plunger, and when the plate 28v has beenswung downwardly. into contact with the, faceJZ of the block II the pressure is again antomatically-applied to the piston I! while pressure.

is discontinuedthrough theportAUto the plunger.

It will be readily appreciated that numerous formsof-control devicesin the formof relays,

switches and .valves may .be-utilized to accomplish the sequence of operations of the various elements.

of this. machine, as has been herein described.

In the operation of a machine-such as described it is sometimes found necessary to clear the in: jection nozzle of plastic material which may flow therefrom. during the periods when the pressure maybe relieved and in orderto accomplishthis resultthe hydraulic pressure to the cylinders 6| may be reversed sothat the-plungers will be forced outwardly to move the die holder 1 in the direction of the die holderB, while thetoggle is raised,

thereby. moving the block 1 anditsdie clear of v the injection nozzle 6 and. permitting access thereto for cleaning or repair.

What Iclaim as my invention is;

1. In a plastic molding machine, the combina- 7 tion with a pair of separable dies, of, toggle links:

connected with one of said dies to move same toward and fromthe other of said dies, a strut plate separate from said toggle links adaptedto be and lock the toggle operated die, hydraulic means '40 moved without compressive pressure .to engagearrangeduin angular relationtosaidstrut plate a to move same intoand out of lockingposition,v and hydraulic means for-applyingcompressive.

8 draulicmeanspivotally connected to and extend-, lug-substantially right angularlylromsaid strut platejor raising and lowering said toggle to move thatoggle-connectednie from and to themating 3. In a machine asnclaimed in claimv.2,va -hydraulic, ,cylinder -mounted on horizontal pivots to swing; ina verticalplane havinghollow trunnion-pivot'supportaa port leading from onehof saidwhollow trunnionsto the bottom end of said, cylinder-,e porteleading from the other of said trunnions to thefitop of said cylinder, andoa. plungerv mountedtin said cylinder and pivotally connected atits upper end with thelockingstrut plate-piyotally connected with the hydraulicallyoperatedsmember in said abutment.

4. A plastic molding "machine comprising ,a base; an abutment-mountedat one end voi -said base, ,a flange rigid-with-said base spaced fromsaidrabutment, horizontal tie rods extending from; 'said;abutment to said-flange, a die block holder, mounted on said tie rodsadjacent to said flange. a die blochholdenslidably mounted on-said tie, rodsbetweenthe aforesaid holder and said abutment, a horizontally movable-hydraulically oper I ated member mounted in said abutment, toggle links connecting said hydraulically operated member with said slidable: die blockholder,- a rigid member extending from the toggle member. connected to said hydraulically operated member; 1 and adapted to engage in looking contact withsaid slidable die-block holder toform a rigidstrut erebe ween d m nsi n operetinesaid i locking meinber to first clearthe rigid member fromlocking contactwith the die block holden; thenrnoving said; die block holder longitudinally on-said tie rod, and then returningthe die block holder and locking sameprior to the application of compression pressure by said hydraulically ra e m m s 5. Aplastic molding injection machine, com prisinga base, an injection cylinder plunger and a heating cylindenconnected therewith mounted on said base, a diehqlder movably mounted on said 5 base; a pair of hydraulic cylinders mounted upon pressure directly to said. strutrplaterand die following thecompletion. of therclosingamovement of said strut plate and toggle links.

2. In a plastic molding machine, v the combination with a pair of separable dies, of togglelinks pivotally connected to one of said dies, an abutment arranged in opposed relation to the latter,

die, a hydraulically operated member mounted in saidabutment, toggle links pivotally connected to said hydraulically .operated member and.piv otally connected to the aforesaid toggle links' and arranged-one at either-side of said injection cylinder, .plungersmounted in saidpair of hydraulic. cylinders rigidly connected to said movable die holder, means for directinghydraulic '50 fiuidpressure into said pair of cylinders to operate, said plungers to exert a pulling force between; saiddnJ'ectionCyhnder andsaid die block'in opposition to the pressure exerted against the die bloclgby the ram of the injection-cylinder, a die block movably'mounted to and from engagement a rigid, strut plate carried by the togglelinkconnected to the hydraulically operated memberarranged to engagein locking .contactfree from.

endwise pressure between the .die, connected to ber-to form a rigid strut therebetween, and hy:

with,.the aforesaid .die block, means for moving the latter die block toand from engagement with the. aforesaid dieblock, .and means for exerting, hydraulic pressure against said movable die block 00 in oppositionto the pressure exerted thereagainst saidtoggle and said hydraulically operatedmem ARTHUR A. BURRY. 

